Add "unitHelp" attribute

I'm aware I that I can use the production phase to do essentially the same thing. However, currently there is no way to prevent the additional non combat units needed from cluttering the "unit help" feature. This side effect renders the "unit help" to cumbersome to be as useful as first intended. Especially for the noobies, it becomes a source of confusion instead.

So here is another suggestion for feature.

An attribute which can set, if this unit will be displayed in "unit help". Maybe in the "unitAttachment" as so.

@alkexr
Either location will function, but in unit attachments is ideal.

The unit help page can get very cluttered with non combat units, which have no stats. It would be very good for the game, to allow map makers and modders to decide what units are important enough to be included there. Having a bunch of the same exact dummy units for every nation, makes it a pain in the ass to quickly look up what a unit can do, especially if the unit is specific to a nation.

In my view, it does affect game mechanics indirectly. Because its affecting my decision to proceed with a design that dictates a very integral element of game mechanics. A completely overhauled technology model, that will not involve any chance.

@general_zod There is a very similar problem: if a map has units with abstracted AA, many different kinds of support, and maybe other properties as well, the unit tooltip (ctrl + i over the unit) is going to be cluttered with all sorts of incomprehensible stuff. That's why the map maker can decide to create a "tooltips.properties" file whithin the map folder (check Greyhawk Wars), where they can specify exactly what the tooltip should be for each unit. I think this case is very similar, and should either get its own "unithelp.properties" file, or go into the "tooltips.properties" file.